/**************************************************************************************************
 * MurmurHash3 was written by Austin Appleby, and is placed in the
 * public domain. The author hereby disclaims copyright to this source
 * code.
 *************************************************************************************************/

#include "murmur3.h"
#include <string.h>

#if !defined(__x86_64__) || defined(IW_TESTS)
IW_INLINE uint32_t rotl32(uint32_t x, int8_t r) {
  return (x << r) | (x >> (32 - r));
}
#endif

IW_INLINE uint64_t rotl64(uint64_t x, int8_t r) {
  return (x << r) | (x >> (64 - r));
}

#define ROTL32(x,y) rotl32(x,y)
#define ROTL64(x,y) rotl64(x,y)

static uint32_t seed_value = 0x2fa1bca;

// Finalization mix - force all bits of a hash block to avalanche
#if !defined(__x86_64__) || defined(IW_TESTS)
IW_INLINE uint32_t fmix32(uint32_t h) {
  h ^= h >> 16;
  h *= 0x85ebca6b;
  h ^= h >> 13;
  h *= 0xc2b2ae35;
  h ^= h >> 16;
  return h;
}
#endif

IW_INLINE uint64_t fmix64(uint64_t k) {
  k ^= k >> 33;
  k *= 0xff51afd7ed558ccdLLU;
  k ^= k >> 33;
  k *= 0xc4ceb9fe1a85ec53LLU;
  k ^= k >> 33;
  return k;
}

#if !defined(__x86_64__) || defined(IW_TESTS)

void murmur3_x86_32(const void *key, size_t len, uint32_t seed, void *out) {
  const uint8_t *data = (const uint8_t *)key;
  const size_t nblocks = len / 4;
  size_t i;
  uint32_t h1 = seed;
  uint32_t c1 = 0xcc9e2d51;
  uint32_t c2 = 0x1b873593;

  const uint32_t *blocks = (const uint32_t *)(data + nblocks * 4);
  for (i = -nblocks; i; i++) {
    uint32_t k1;

    memcpy(&k1, blocks + i, sizeof(k1));

    k1 *= c1;
    k1 = ROTL32(k1, 15);
    k1 *= c2;
    h1 ^= k1;
    h1 = ROTL32(h1, 13);
    h1 = h1 * 5 + 0xe6546b64;
  }

  const uint8_t *tail = (const uint8_t *)(data + nblocks * 4);
  uint32_t k1 = 0;
  switch (len & 3) {
    case 3:
      k1 ^= (uint32_t)tail[2] << 16;
    /* fallthrough */
    case 2:
      k1 ^= (uint32_t)tail[1] << 8;
    /* fallthrough */
    case 1:
      k1 ^= (uint32_t)tail[0];
      k1 *= c1;
      k1 = ROTL32(k1, 15);
      k1 *= c2;
      h1 ^= k1;
      /* fallthrough */
  };

  h1 ^= (uint32_t)len;
  h1 = fmix32(h1);
  *(uint32_t *) out = h1;
}

void murmur3_x86_128(const void *key, const size_t len, uint32_t seed, void *out) {
  size_t i;
  const uint8_t *data = (const uint8_t *)key;
  const size_t nblocks = len / 16;

  uint32_t h1 = seed;
  uint32_t h2 = seed;
  uint32_t h3 = seed;
  uint32_t h4 = seed;

  const uint32_t c1 = 0x239b961b;
  const uint32_t c2 = 0xab0e9789;
  const uint32_t c3 = 0x38b34ae5;
  const uint32_t c4 = 0xa1e38b93;

  const uint32_t *blocks = (const uint32_t *)(data + nblocks * 16);

  for (i = -nblocks; i; i++) {
    uint32_t k1, k2, k3, k4;

    memcpy(&k1, blocks + i * 4 + 0, sizeof(k1));
    memcpy(&k2, blocks + i * 4 + 1, sizeof(k2));
    memcpy(&k3, blocks + i * 4 + 2, sizeof(k3));
    memcpy(&k4, blocks + i * 4 + 3, sizeof(k4));

    k1 *= c1;
    k1 = ROTL32(k1, 15);
    k1 *= c2;
    h1 ^= k1;
    h1 = ROTL32(h1, 19);
    h1 += h2;
    h1 = h1 * 5 + 0x561ccd1b;
    k2 *= c2;
    k2 = ROTL32(k2, 16);
    k2 *= c3;
    h2 ^= k2;
    h2 = ROTL32(h2, 17);
    h2 += h3;
    h2 = h2 * 5 + 0x0bcaa747;
    k3 *= c3;
    k3 = ROTL32(k3, 17);
    k3 *= c4;
    h3 ^= k3;
    h3 = ROTL32(h3, 15);
    h3 += h4;
    h3 = h3 * 5 + 0x96cd1c35;
    k4 *= c4;
    k4 = ROTL32(k4, 18);
    k4 *= c1;
    h4 ^= k4;
    h4 = ROTL32(h4, 13);
    h4 += h1;
    h4 = h4 * 5 + 0x32ac3b17;
  }

  const uint8_t *tail = (const uint8_t *)(data + nblocks * 16);

  uint32_t k1 = 0;
  uint32_t k2 = 0;
  uint32_t k3 = 0;
  uint32_t k4 = 0;

  switch (len & 15) {
    case 15:
      k4 ^= (uint32_t)tail[14] << 16;
    /* fallthrough */
    case 14:
      k4 ^= (uint32_t)tail[13] << 8;
    /* fallthrough */
    case 13:
      k4 ^= (uint32_t)tail[12] << 0;
      k4 *= c4;
      k4 = ROTL32(k4, 18);
      k4 *= c1;
      h4 ^= k4;
    /* fallthrough */
    case 12:
      k3 ^= (uint32_t)tail[11] << 24;
    /* fallthrough */
    case 11:
      k3 ^= (uint32_t)tail[10] << 16;
    /* fallthrough */
    case 10:
      k3 ^= (uint32_t)tail[ 9] << 8;
    /* fallthrough */
    case  9:
      k3 ^= (uint32_t)tail[ 8] << 0;
      k3 *= c3;
      k3 = ROTL32(k3, 17);
      k3 *= c4;
      h3 ^= k3;
    /* fallthrough */
    case  8:
      k2 ^= (uint32_t)tail[ 7] << 24;
    /* fallthrough */
    case  7:
      k2 ^= (uint32_t)tail[ 6] << 16;
    /* fallthrough */
    case  6:
      k2 ^= (uint32_t)tail[ 5] << 8;
    /* fallthrough */
    case  5:
      k2 ^= (uint32_t)tail[ 4] << 0;
      k2 *= c2;
      k2 = ROTL32(k2, 16);
      k2 *= c3;
      h2 ^= k2;
    /* fallthrough */
    case  4:
      k1 ^= (uint32_t)tail[ 3] << 24;
    /* fallthrough */
    case  3:
      k1 ^= (uint32_t)tail[ 2] << 16;
    /* fallthrough */
    case  2:
      k1 ^= (uint32_t)tail[ 1] << 8;
    /* fallthrough */
    case  1:
      k1 ^= (uint32_t)tail[ 0] << 0;
      k1 *= c1;
      k1 = ROTL32(k1, 15);
      k1 *= c2;
      h1 ^= k1;
      /* fallthrough */
  }

  h1 ^= (uint32_t)len;
  h2 ^= (uint32_t)len;
  h3 ^= (uint32_t)len;
  h4 ^= (uint32_t)len;

  h1 += h2;
  h1 += h3;
  h1 += h4;
  h2 += h1;
  h3 += h1;
  h4 += h1;

  h1 = fmix32(h1);
  h2 = fmix32(h2);
  h3 = fmix32(h3);
  h4 = fmix32(h4);

  h1 += h2;
  h1 += h3;
  h1 += h4;
  h2 += h1;
  h3 += h1;
  h4 += h1;

  ((uint32_t *)out)[0] = h1;
  ((uint32_t *)out)[1] = h2;
  ((uint32_t *)out)[2] = h3;
  ((uint32_t *)out)[3] = h4;
}
#endif

void murmur3_x64_128(const void *key, const size_t len, const uint32_t seed, void *out) {
  const uint8_t *data = (const uint8_t *)key;
  const size_t nblocks = len / 16;
  size_t i;
  uint64_t h1 = seed;
  uint64_t h2 = seed;
  uint64_t c1 = 0x87c37b91114253d5LLU;
  uint64_t c2 = 0x4cf5ad432745937fLLU;

  const uint64_t *blocks = (const uint64_t *)(data);
  for (i = 0; i < nblocks; i++) {
    uint64_t k1, k2;

    memcpy(&k1, blocks + i * 2 + 0, sizeof(k1));
    memcpy(&k2, blocks + i * 2 + 1, sizeof(k2));

    k1 *= c1;
    k1 = ROTL64(k1, 31);
    k1 *= c2;
    h1 ^= k1;
    h1 = ROTL64(h1, 27);
    h1 += h2;
    h1 = h1 * 5 + 0x52dce729;
    k2 *= c2;
    k2 = ROTL64(k2, 33);
    k2 *= c1;
    h2 ^= k2;
    h2 = ROTL64(h2, 31);
    h2 += h1;
    h2 = h2 * 5 + 0x38495ab5;
  }

  const uint8_t *tail = (data + nblocks * 16);
  uint64_t k1 = 0;
  uint64_t k2 = 0;
  switch (len & 15) {
    case 15:
      k2 ^= (uint64_t)(tail[14]) << 48;
    /* fallthrough */
    case 14:
      k2 ^= (uint64_t)(tail[13]) << 40;
    /* fallthrough */
    case 13:
      k2 ^= (uint64_t)(tail[12]) << 32;
    /* fallthrough */
    case 12:
      k2 ^= (uint64_t)(tail[11]) << 24;
    /* fallthrough */
    case 11:
      k2 ^= (uint64_t)(tail[10]) << 16;
    /* fallthrough */
    case 10:
      k2 ^= (uint64_t)(tail[9]) << 8;
    /* fallthrough */
    case 9:
      k2 ^= (uint64_t)(tail[8]) << 0;
      k2 *= c2;
      k2 = ROTL64(k2, 33);
      k2 *= c1;
      h2 ^= k2;
    /* fallthrough */
    case 8:
      k1 ^= (uint64_t)(tail[7]) << 56;
    /* fallthrough */
    case 7:
      k1 ^= (uint64_t)(tail[6]) << 48;
    /* fallthrough */
    case 6:
      k1 ^= (uint64_t)(tail[5]) << 40;
    /* fallthrough */
    case 5:
      k1 ^= (uint64_t)(tail[4]) << 32;
    /* fallthrough */
    case 4:
      k1 ^= (uint64_t)(tail[3]) << 24;
    /* fallthrough */
    case 3:
      k1 ^= (uint64_t)(tail[2]) << 16;
    /* fallthrough */
    case 2:
      k1 ^= (uint64_t)(tail[1]) << 8;
    /* fallthrough */
    case 1:
      k1 ^= (uint64_t)(tail[0]) << 0;
      k1 *= c1;
      k1 = ROTL64(k1, 31);
      k1 *= c2;
      h1 ^= k1;
      /* fallthrough */
  };

  h1 ^= (uint64_t)len;
  h2 ^= (uint64_t)len;
  h1 += h2;
  h2 += h1;
  h1 = fmix64(h1);
  h2 = fmix64(h2);
  h1 += h2;
  h2 += h1;
  ((uint64_t *) out)[0] = h1;
  ((uint64_t *) out)[1] = h2;
}

uint32_t murmur3(const char *keyptr, size_t len) {
#ifdef __x86_64__
  uint64_t hash[2];
  murmur3_x64_128(keyptr, len, seed_value, hash);
  return (uint32_t) hash[1];
#else
  if (len <= 16) {
    uint32_t hash;
    murmur3_x86_32(keyptr, len, seed_value, &hash);
    return hash;
  }
  uint32_t hash[4];
  murmur3_x86_128(keyptr, len, seed_value, hash);
  return hash[3];
#endif
}

void murmur3_set_seed(const uint32_t seed) {
  seed_value = seed;
}
